Decorator

Decorator Design Pattern attaches additional responsibility to an object dynamically. This pattern provides a flexible alternative to subclassing for extending functionality

Overview

The Decorator pattern allows behavior to be added to objects dynamically without altering their structure. It provides a flexible alternative to subclassing for extending functionality by wrapping objects in decorator classes that contain the same interface.

Implementation Details

This implementation demonstrates a pizza ordering system where different toppings can be added to a base pizza:

Key Components:

• IPizza Interface: Common interface for both concrete pizzas and decorators
• PlainPizza (Concrete Component): The base pizza implementation
• PizzaDecorator (Base Decorator): Abstract decorator class that implements IPizza
• Concrete Decorators: ChickenPizzaDecorator and VegPizzaDecorator that add specific toppings

Classes:

• IPizza - Component interface with MakePizza() method
• PlainPizza - Concrete component representing a basic pizza
• PizzaDecorator - Abstract decorator class that wraps an IPizza object
• ChickenPizzaDecorator - Concrete decorator that adds chicken topping
• VegPizzaDecorator - Concrete decorator that adds vegetable topping

Usage Example:

PlainPizza plainPizza = new();
Console.WriteLine(plainPizza.MakePizza()); // "Plain Pizza"

PizzaDecorator chickenPizza = new ChickenPizzaDecorator(plainPizza);
Console.WriteLine(chickenPizza.MakePizza()); // "Plain Pizza, Chicken"

PizzaDecorator vegPizza = new VegPizzaDecorator(plainPizza);
Console.WriteLine(vegPizza.MakePizza()); // "Plain Pizza, Veg"

// Can also chain decorators
PizzaDecorator deluxePizza = new VegPizzaDecorator(chickenPizza);
Console.WriteLine(deluxePizza.MakePizza()); // "Plain Pizza, Chicken, Veg"

Benefits:

• Adds functionality to objects without modifying their structure
• More flexible than static inheritance
• Allows for dynamic composition of behaviors
• Follows Single Responsibility Principle
• Supports unlimited combinations of decorators